The Factors Of Choosing The Centrifugal Fan

Date:19-10-2017

Abstract:

Centrifugal fan working principle and turbine compresso […]

Centrifugal fan working principle and turbine compressor is basically the same, are due to low gas flow rate, the pressure change is not, generally do not need to consider the gas specific volume changes, that is, the gas as incompressible fluid treatment.

Centrifugal fans rely on the input of mechanical energy, to improve the gas pressure and send the gas to the machinery. Its centrifugal fans are widely used in factories, mines, tunnels, cooling towers, vehicles, ships and buildings for ventilation, dust and cooling. In general, we need to determine two key parameters before we prepare the fan: air volume and wind pressure. According to the unused air volume and wind pressure, to select the appropriate fan. For air conditioning equipment, the wind pressure is usually selected by full pressure.

For forward centrifugal fans, it has the advantage of low cost, fast speed, you can use smaller shafts and smaller bearings, and has a wide operating range. The disadvantage is that the shape of the performance curve may be parallel to the pipe network resistance curve, the system static pressure reduction may lead to motor overload. In addition, the blade structure strength is relatively low, can not run in the higher speed. As the fan power curve has increased tendency, is "easy to overload" fan, so the best pressure is best not to exceed 1200Pa.

For backward centrifugal fans, it has the advantage of high efficiency and the power curve is not overloaded. The power curve usually reaches the maximum in the middle of the common range, so that it is not overloaded. The blade and impeller's own structural strength is relatively high, and a higher hydrostatic system can be used. But the disadvantage is due to the impeller running speed, so the need for thick shaft and large bearings. In addition, the fluctuation of static pressure is easy to cause the change of working condition. The improvement of the rear centrifugal fan is to replace the blades of the wing section with the blade of the cross section, which improves the hydrostatic efficiency of the fan to about 86%, and reduces the noise of the fan accordingly. The well-designed wing The noise of the blade fan is even lower than the tilting centrifugal fan.